Questions tagged [electromagnetic-induction]

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IN 3 phase transformer the winding are 180 degree out of phase and where it is used as application

application of 180 phase shift transformer am a novice in electrical engineering. I notice that in transformer the secondary side current & current referred to as primary are 180 degree out of ...
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22 views

Magnet oscillation with coils

I am trying to conduct an experiment in which I will try to find the natural frequency of a cantilever. To oscillate the cantilever, I thought I could use a magnet and a current-carrying coil wire ...
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Electric Field in conductor near Solenoid

My question is essentially a follow up to this question. It's answer says, the mobile charges in the conductor distribute themselves to make E = 0 inside the conductor. But, I don't understand how a ...
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Question about induced current with an axis parallel to magnetic field

I am currently going over a physics test. One of the questions asked if a square loop of wire perpendicular to a uniform magnetic field entering the page has an induced charge if it is spun ...
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69 views

Experiment: Magnet falling in a copper/aluminum pipe

We know that when we release a magnet in conducting pipe (aluminum, copper, etc..) it will be subjected to a magnetic force induced by the induced current. This magnetic field will be created in a ...
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Calculation of eddy currents and subsequent heating in a metal, ATEX-rated junction box

We are building a system which will make use of a stainless steel junction box to connect different circuits within it. This will be located in a hazardous offshore environment so we will be using an ...
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Why does inductor current lag the applied voltage at its terminal by 90 degrees?

I studied electromagnetism and I am currently working with Inductors. I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 ...
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Magnet moving between $2$ separate coils, connected to a circuit

I was thinking about a question regarding a magnet entering a coil when the following thought came: what if we unravelled the middle of the coil such that it splits into $2$ equal parts, and connected ...
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Constructing an equation for the induced EMF, in terms of the radius of a circular loop [on hold]

In order to calculate for the curl of the induced electric field for a loop moving in a uniform magnetic field, and using the cylindrical coordinate system for a curl, it's my understanding that since ...
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142 views

Current in only inductive AC circuit

Current through a LR circuit is given by $$i=i_0 (1-e^{\frac{-tR}{L}})..1$$From here I can observe that as I tend R towards 0 no current flows through the circuit , and current will be 0 when the ...
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47 views

What is actually being removed when a metal conductor is grounded?

I found this image earlier this morning, and yes, there are a lot of diagrams/illustrations about this, transferring charges by induction has been introduced since the very beginning of high school ...
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1answer
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Does grounding set the potential on a surface of a sphere to $~0~$ or the potential due to the charges of the sphere to $~0~$?

I'm understand that grounding sets the potential to $0$, but I'm confused as to which potential it sets to $0$. Let me explain my question: If I have a sphere and I bring a positive charge near it, a ...
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Regarding the use of Ampere's Law

i wanted to calculate $\mathbf{B}$ of these two parallel wires, and i've taken a glance at the correction and i've found out this equation, i tried to understand it but in vain, where do $(x + \frac{d}...
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Electric field due to changing uniform magnetic field

I think this could be a misunderstanding on my part , still I want to clarify this.Suppose in a region of boundless expanse, there is a uniform magnetic field which changes at a rate $\frac{d\phi}{dt}$...
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How to acquire the individual components of electric field (x,y,z) for a EMF induced in a circular loop?

I am trying to calculate the curl of the electric field induced in circular loop of wire. In order to do the actual cross the product, I would require the x,y,z component of the electric field induced ...
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Is there a way to express the curl of the electric field in the integral form?

In order to experimentally measure the curl of the electric field from faraday's law... is there a way to equate the curl of the electric field to some integral that are measurable in a practical ...
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How to compute the curl of the electric field, experimentally?

In order to experimentally verify Faraday's law and express the curl of the induced electric field, is there any other way to compute the curl without directly working on the cross product (ie working ...
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Investigating the relationship between a changing B field and the curl of the electric field induced

I am currently working on a 12 page lab report on Faraday's law, essentially investigating, how for different magnetic field strength through a stationary loop of wire with N number of turns, effects ...
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31 views

What is $v(t)$ in a sliding conducting rail in a magnetic field?

This is problem 7.7c from David J. Griffiths - Introduction to Electrodynamics. A metal bar of mass $m$ slides frictionlessly on two parallel conducting rails a distance $l$ apart. A resistor $R$ ...
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2answers
102 views

Why doesn't current cancel in a generator?

I am a little confused about the application of Faraday's law in a generator. If we imagine a magnet attached to a wheel (which spins when water falls on it) next to a coil, as the magnet spins around,...
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63 views

Experimentally defining Faraday's law [closed]

I am a highschool student, and I currently writing a lab on the how the curl of the electric field (with respect to the induced emf) is effected by changing the strength of the magnetic field for each ...
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332 views

How is it possible for the induced emf to take negative values in Faraday's Law of induction?

Faraday's Law of induction states that the work done per unit charge by the (induced) electric force along a loop of wire, or the emf, is minus the rate of change of magnetic flux through the loop/...
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Rate of change of area of a circular loop exiting a uniform magnetic field

The question is to find the variation in induced electromotive force w.r.t to time or put simply $\varepsilon(t)$ for a circular loop being removed from the region of the magnetic field at a constant ...
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Can electricity be generated using a rotating electromagnet and fixed metal plates enclosing it (as opposed to rotating permanent magnet)?

I was wondering , if this be possible , can we make an adjustable electricty generator? If not, why so? Appreciate any responses .
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Potential drop across inductors in DC circuits

The potential drop across an inductor is equal to $L(di/dt)$ where $L$ is inductance coefficient. But according to this in a DC circuit there should be no potential drop across the inductor (because $...
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Quantum Mechanical Treatment of the Spin Echo

I'm trying to find the expectation value of the spin in the $y$ direction after applying a $\pi/2$-$\pi/2$ sequence of pulses. In Slichter's Principles of Magnetic Resonance, he does a $\pi/2$-$\pi$ ...
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How is the magnetic flux density inside a current tube affected by an inner wire?

Background to problem Conventional wisdom informs that the magnetic flux density inside a tube carrying current is zero everywhere. Pictorially this is represented by this finite element analysis (...
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Direction of EMF and Induced current through the circuit

When the circuit shown above is moved with a constant velocity to the left I know that B is going to have the higher potential. And I believe that the current flows clockwise that is in the sense of ...
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What is the main mechanism for induction heaters (cookers)?

I thought that induction heaters (as used in cooking) relied on Joule heating losses due to Eddy currents induced by an oscillating magnetic field, produced by an inductor through which AC runs ...
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71 views

How Is Induction Energy Transferred From a Toroidal Solenoid To An External Conductor During Linear Current Change?

It is widely understood that $\nabla \times \vec A =\vec B = 0$ outside a toroidal solenoid with constant current, $I=k$ ($I = \vec J$ in the below illustration). It is not so widely understood that ...
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48 views

Do magnetic field lines actually cancel?

Typically when explaining why parallel conducting wires attract, it is said that their magnetic fields cancel out (in the case of same direction current) and hence produces an attraction force due to ...
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MHD pump liquid metal flow speed

a rather simple question, are there any studies or some information about the flow speed of liquid metal inside a tube? My setup is basically a 50cm diameter circular tube (could be another diameter) ...
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Nature of induced emf in Faraday's law

When there is a battery in a simple circuit loop, for instance, there is a real low potential terminal and a high potential terminal , the battery does work on charges and delivers them at high ...
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59 views

How is the rate of current change in an inductor present in a circuit maintained / decreased?

Considering an ideal circuit of DC voltage source and an inductor connected together with a switch in between them. When the switch is closed at t=0 the current starts increasing which causes induced ...
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A parallel between eddy current and Beer-Lambert law

For AC current flowing in wire eddy currents are the reason for current density decay as we move towards the center. Similarly, in Beer-Lambert law, for electromagnetic plane wave impinging on ...
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1answer
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How can diamagnetism levitate anything?

From the explanation of diamagnetism that I was given, the electrons when exposed to a changing magnetic field will change their spin in accordance to Lenz's law. This will induce an opposing magnetic ...
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Potential due to initially uncharged induced conductor?

From Griffiths' Introduction to electrodynamics: In this problem, Griffiths says that we will set the potential inside and on the surface of the conductor to be zero since its an equipotential ...
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Confusion in understanding the behavior of inductor in RL circuit with DC source

When we have a DC voltage source with a switch in series with $RL$ and the switch is closed at $t=0$ then it is said that current is zero initially, but the voltage across inductor is same as that of ...
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flux threading through superconducting ring

I have been confused over the wording used in this paper describing RSFQ logic circuits: http://www.mukhanov.com/uploads/LikharevSemenov-RSFQReview_IEEETAS91.pdf From page 6: " If such a single flux ...
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87 views

What does direction of EMF mean?

In faraday's law it mention's direction of EMF( like in closed loopit is clockwise or anticlockwise depending on direction of motion of magnet) but defination of EMF is roughly Potential diffrence ...
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Inducing coil current by falling?

Typically, if a rod or coil is moved at a constant velocity through a constant magnetic field, a motional EMF will be induced by Faraday's Law but no current because there is no net emf or no closed ...
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How long does it take for this coil to stop? [closed]

Let's suppose there's a horizontal and uniform magnetic field $B$, and we introduce from below the field a square coil of mass $m$, side length $a$ and resistance $R$ in it with a inicial velocity $...
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Direction of integration and boundary limits in electromagnetism?

I have encountered several problems regarding the choice of direction of integration and the boundary limits, this semester in electromagnetism. Is there some rule, so I don't do it wrong again. In ...
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How to calculate induced emf of moving rod?

I have the following exercise: A copper rod with length L is moving on two frictionless conducting rails, in a distance a from an very long straight conductor. The rods resistance: R. Ignore any self ...
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32 views

Change in Magnetic Flux: Eddy Currents vs Moving Wire

From what I have read, as a conducting rod moves perpendicular to a uniform magnetic field, this will lead to a change in magnetic flux and therefore an emf will be induced (area being swept as the ...
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1answer
31 views

Lenz's law analogy in optics?

Probably a stupid question, but I am wondering if there is an effect similar to Lenz's/Faraday's law of induction, but in optics. That is, rather than a changing magnetic field inducing a voltage in ...
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Basic Transformer Question

My understanding of how a transformer works is that there is a primary and a secondary coil wrapped around a common iron coil. An alternating current in the primary coil results in a changing ...
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Is it possible to use Ampere's law to calculate vector B around short straight line conductor?

Maybe this question sounds easy, but I would really be grateful if someone could give me an explanation if it's true or not. I'm not sure if I understand it good enough.